"We're really a baseball house," she told PEOPLE during a press event in Los Angeles to promote her new film, Draft Day. "When I was first dating Ben, I'd never watched baseball. I didn't really care, I may say, about baseball."
"But if you watch three or four games in a row, you learn just enough to hook you in. And it's the same as a soap opera, right? If you watch three or four, you get just enough of a storyline to grab you, and that's why people are so into them."
"Now, I'm totally addicted to baseball. But believe me, when the playoffs happen, it's all about Tom Brady, all the time," she says.
Starring alongside Kevin Costner in Draft Day, which tells the story of the Cleveland Browns, the film allowed Garner, 41, to reconnect with her love of football.
"I grew up in West Virginia which is very much how you picture Texas, where Friday Night Lights [takes place]. Every Friday night, we're at the game," she says.
"I was at every single game because I was in the marching band. And then, my senior year, I left the marching band – which was a scandal at the time – and I was the water girl for the team. So I traveled with them. I didn't miss a game, and I loved it."
But even Garner's days as a football fan have changed since having a family.
"Now that I have kids, my husband will have the Patriots on, and I see what's happening," she says. "But I'm running around making sure that he can sit and watch calmly is really what's happening!"
Reporting by SCOTT HUVER